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Endogenous Retroviruses - Frequently Asked Questions

This page lists frequently asked questions (FAQs)from creationists about the case for common descentfrom endogenous retroviruses (ERVs). These are specific markers that establish, beyond any reasonable doubt, the truth of common descent.

Each question links to its answer.

If you wish to ask further questions or discussany entries, post your questions or commentsin the discussion section below, or join the FaceBook group, ERV.

21 comments:

Perhaps ERV-like sequences are sources of escaped genes that contribute to the genesis of retroviruses. Perhaps retroviruses precede the establishment of ERVs, as is observed today. Perhaps both are true in different instances.

Retroviruses produce ERVs, but ERVs have also (rarely) been observed to produce retroviruses. Some creationists speculate that ERVs were designed as tools of genetic engineering, to produce retroviruses and spread genetic material around, and were installed independently in different species. There are problems with this idea.

1) Retroviruses are pretty indiscriminate as to where they integrate their DNA. This can cause severe problems, and this is why there is so much excitement at the moment of writing about CRISPR, which is a precise genetic engineering/therapy/research tool that does not have these problems. It's not a very good way of

2) Most ERVs are faulty. Disabled by mutation and methylation (thank goodness). The disabling mutations are largely the same in closely related species. See http://barryhisblog.blogspot.fr/p/the-natural-history-of-retroviruses.html

Barry I've argued with creationists before who have made the same case that all retroviruses we have today came from the ERVs we were designed with.

One of the major flaws with this argument is the fact that many of our ERVs are flanked by two near identical LTRs which conform to the pattern U3-R-U5. We know exactly how these duplicate LTRs are formed - they are formed in the reverse transcription process from RNA to DNA.

http://www.microbiologybook.org/flash/hiv-ltr-fn.html

In other words if we ever see and ERV in our DNA flanked by LTRs (and there are tens of thousands of these which are shared with chimpanzees in identical locations), then we can be absolutely sure that this sequence is foreign to our genome and came from a retroviral infection at some point in our past.

The other point to make is that the experiments with the reconstructed Phoenix HERV-K retrovirus demonstrated that you have to remove the mutations from the ERVs in order to get functional retrovirus. If retroviruses were inserting into genomes to produce ERVs, and subsequent mutations altered the ERVs further from that original and functional retroviral genome, then a consensus sequence of different ERVs should give you the original retrovirus genome, and it should be functional. That's exactly what we see. When you line up the ERVs and use them to produce a consensus sequence, that consensus sequence produces a viable retrovirus that also inserts into the same types of genomic motifs (of which there are millions in the human genome) that we find ancient HERV-K insertions.

To use an analogy, you don't conclude that the cars at a junkyard are on their way to becoming new cars. ERVs have all of the dents and rust that you would expect from an ancient insertion.

Here I am, Mr Barry, and so far I have seen no text of yours that accounts for the issues with the potential detrimental effects posed by uncontrolled ERV insertions and activity accumulating during millions of years prior to the evolution of the mechanisms that tightly control these retroviral elements (for example, more than 40 genes are required to properly regulate the ERV's...)

ERV integrations, like mutations from other sources, are more likely to be detrimental than advantageous. The detrimental ones become extinct because their carriers fail to reproduce so well. The advantageous ones tend to tend to increase in frequency in the population, because they aid successful reproduction. Th eprocess is known as the natural selection of advantageous heritable variations.

I'm interested, Anon. Do you have an alternative explanation for correspondingly localised ERVs in different species?

Thank you, David! :) For other readers, Graeme Finlay's book, Human Evolution, is a great source on ERVs and other genetic markers that ceryify common descent. For those who deny common descent for "religious" reasons, Finlay happens to be a Christian.

http://www.sciencemag.org/news/2016/03/viral-fossils-our-dna-may-help-us-fight-infection?utm_source=sciencemagazine&utm_medium=facebook-text&utm_campaign=viralfossils-2747Viral ‘fossils’ in our DNA may help us fight infection

Folks, this is someone who posts garbage on a Facebook "Intelligent Design" group. He gives the lie to the assertion that Intelligent Design enthusiasts are not just dishonest (is there any other sort?) creationists.